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diff --git a/doc/dw-images-and-backgrounds.doc b/doc/dw-images-and-backgrounds.doc deleted file mode 100644 index 8f07766a..00000000 --- a/doc/dw-images-and-backgrounds.doc +++ /dev/null @@ -1,235 +0,0 @@ -/** \page dw-images-and-backgrounds Images and Backgrounds in Dw - -Image Buffers -============= - -Representation of the image data is done by dw::core::Imgbuf, see -there for details. Drawing is done by dw::core::View -(dw::core::View::drawImage). - -Since dw::core::Imgbuf provides memory management based on reference -counting, there may be an 1-to-n relation from image renderers (image -widgets or backgrounds, see below) and dw::core::Imgbuf. Since -dw::core::Imgbuf does not know about renderers, but just provides -rendering functionality, the caller must (typically after calling -dw::core::Imgbuf::copyRow) notify all renderers connected to the -buffer. - - -Image Renderer -============== - -Generally, there are no restrictions on how to manage -dw::core::Imgbuf; but to handle image data from web resources, the -interface dw::core::ImgRenderer should be implemented. It is again -wrapped by DilloImage (to make access from the C part possible, since -dw::core::ImgRenderer is written in C++), which is referenced by -DilloWeb. There are two positions where retrieving image data is -initiated: - -- Html_load_image: for embedded images (implemented by dw::Image, - which implements dw::core::ImgRenderer); -- StyleEngine::apply (search for "case - CSS_PROPERTY_BACKGROUND_IMAGE"): for backgrond images; there are - some implementations of dw::core::ImgRenderer within the context of - dw::core::style::StyleImage. - -Both are described in detail below. Notice that the code is quite -similar; only the implementation of dw::core::ImgRenderer differs. - -At this time, dw::core::ImgRenderer has got two methods (see more -documentation there): - -- dw::core::ImgRenderer::setBuffer, -- dw::core::ImgRenderer::drawRow, -- dw::core::ImgRenderer::finish, and -- dw::core::ImgRenderer::fatal. - - -Images -====== - -This is the simplest renderer, displaying an image. For each row to be -drawn, - -- first dw::core::Imgbuf::copyRow, and then -- for each dw::Image, dw::Image::drawRow must be called, with the same - argument (no scaling is necessary). - -dw::Image automatically scales the dw::core::Imgbuf, the root buffer -should be passed to dw::Image::setBuffer. - -\see dw::Image for more details. - - -Background Images -================= - -Since background images are style resources, they are associated with -dw::core::style::Style, as dw::core::style::StyleImage, which is -handled in a similar way (reference counting etc.) as -dw::core::style::Color and dw::core::style::Font, although it is -concrete and not platform-dependant. - -The actual renderer (passed to Web) is an instance of -dw::core::ImgRendererDist (distributes all calls to a set of other -instances of dw::core::ImgRenderer), which contains two kinds of -renderers: - -- one instance of dw::core::style::StyleImage::StyleImgRenderer, which - does everything needed for dw::core::style::StyleImage, and -- other renderers, used externally (widgets etc.), which are added by - dw::core::style::StyleImage::putExternalImgRenderer (and removed by - dw::core::style::StyleImage::removeExternalImgRenderer). - -This diagram gives an comprehensive overview: - -\dot -digraph G { - node [shape=record, fontname=Helvetica, fontsize=10]; - edge [arrowhead="open", dir="both", arrowtail="none", - labelfontname=Helvetica, labelfontsize=10, color="#404040", - labelfontcolor="#000080"]; - fontname=Helvetica; fontsize=10; - - subgraph cluster_dw_style { - style="dashed"; color="#000080"; fontname=Helvetica; fontsize=10; - - Style [URL="\ref dw::core::style::Style"]; - StyleImage [URL="\ref dw::core::style::StyleImage"]; - Imgbuf [URL="\ref dw::core::Imgbuf", color="#a0a0a0"]; - StyleImgRenderer - [URL="\ref dw::core::style::StyleImage::StyleImgRenderer"]; - ImgRenderer [URL="\ref dw::core::ImgRenderer", color="#ff8080"]; - ImgRendererDist [URL="\ref dw::core::ImgRendererDist"]; - ExternalImgRenderer - [URL="\ref dw::core::style::StyleImage::ExternalImgRenderer", - color="#a0a0a0"]; - ExternalWidgetImgRenderer - [URL="\ref dw::core::style::StyleImage::ExternalWidgetImgRenderer", - color="#a0a0a0"]; - } - - subgraph cluster_dw_layout { - style="dashed"; color="#000080"; fontname=Helvetica; fontsize=10; - - Layout [URL="\ref dw::core::Layout"]; - LayoutImgRenderer [URL="\ref dw::core::Layout::LayoutImgRenderer"]; - } - - subgraph cluster_dw_widget { - style="dashed"; color="#000080"; fontname=Helvetica; fontsize=10; - - Widget [URL="\ref dw::core::Widget", color="#a0a0a0"]; - WidgetImgRenderer [URL="\ref dw::core::Widget::WidgetImgRenderer"]; - } - - subgraph cluster_dw_textblock { - style="dashed"; color="#000080"; fontname=Helvetica; fontsize=10; - - Textblock [URL="\ref dw::Textblock"]; - Word [URL="\ref dw::Textblock::Word"]; - WordImgRenderer [URL="\ref dw::Textblock::WordImgRenderer"]; - SpaceImgRenderer [URL="\ref dw::Textblock::SpaceImgRenderer"]; - } - - Style -> StyleImage [headlabel="*", taillabel="1"]; - StyleImage -> Imgbuf [headlabel="*", taillabel="1"]; - StyleImage -> StyleImgRenderer [headlabel="1", taillabel="1"]; - StyleImage -> ImgRendererDist [headlabel="1", taillabel="1"]; - ImgRendererDist -> StyleImgRenderer [headlabel="1", taillabel="1"]; - ImgRendererDist -> ImgRenderer [headlabel="1", taillabel="*"]; - - ImgRenderer -> ImgRendererDist [arrowhead="none", arrowtail="empty", - dir="both", style="dashed"]; - ImgRenderer -> StyleImgRenderer [arrowhead="none", arrowtail="empty", - dir="both", style="dashed"]; - ImgRenderer -> ExternalImgRenderer [arrowhead="none", arrowtail="empty", - dir="both", style="dashed"]; - ExternalImgRenderer -> ExternalWidgetImgRenderer [arrowhead="none", - arrowtail="empty", dir="both", style="dashed"]; - - Layout -> LayoutImgRenderer [headlabel="1", taillabel="0..1"]; - ExternalImgRenderer -> LayoutImgRenderer [arrowhead="none", - arrowtail="empty", dir="both", style="dashed"]; - - Widget -> WidgetImgRenderer [headlabel="1", taillabel="0..1"]; - ExternalWidgetImgRenderer -> WidgetImgRenderer [arrowhead="none", - arrowtail="empty", dir="both", style="dashed"]; - - Textblock -> Word [headlabel="1", taillabel="*"]; - Word -> WordImgRenderer [headlabel="1", taillabel="0..1"]; - Word -> SpaceImgRenderer [headlabel="1", taillabel="0..1"]; - ExternalWidgetImgRenderer -> WordImgRenderer [arrowhead="none", - arrowtail="empty", dir="both", style="dashed"]; - WordImgRenderer -> SpaceImgRenderer [arrowhead="none", arrowtail="empty", - dir="both", style="dashed"]; -} -\enddot - -<center>[\ref uml-legend "legend"]</center> - - -Memory management ------------------ - -dw::core::style::StyleImage extends lout::signal::ObservedObject, so -that deleting this instance can be connected to code dealing with -cache clients etc. See StyleImageDeletionReceiver and how it is -attached in StyleEngine::apply ("case CSS_PROPERTY_BACKGROUND_IMAGE"). - - -Bugs and Things Needing Improvement -=================================== - -(Mostly related to image backgrounds, when not otherwise mentioned.) - -High Priority -------------- - -**Configurability, security/privacy aspects, etc.,** which are -currently available for image widgets, should be adopted. Perhaps some -more configuration options specially for background images. - - -Medium Priority ---------------- - -**Background-attachment** is not yet implemented, and will be postponed. - -**Calls to dw::core::ImgRenderer::fatal** are incomplete. As an -example, it is not called, when connecting to a server fails. (And so, -as far as I see, no cache client is started.) - - -Low Priority ------------- - -**Alpha support:** (not related to image backgrounds) currently alpha -support (and also colormap management) is done in dicache, while -dw::Image is only created with type RGB. This leads to several problems: - -- One dicache entry (representing an image related to the same URL), - which has only one background color, may refer to different images - with different background colors. -- The dicache only handles background colors, not background images. - -The solution is basicly simple: keep alpha support out of dicache; -instead implement RGBA in dw::Image. As it seems, the main problem is -alpha support in FLTK/X11. - - -Solved (Must Be Documented) ---------------------------- - -*Drawing background images row by row may become slow. As an -alternative, dw::core::ImgRenderer::finish could be used. However, -drawing row by row could become an option.* There is now -dw::core::style::drawBackgroundLineByLine, which can be changed in the -code, and is set to *false*. The old code still exists, so changing -this to *true* activates again drawing line by line. - -(For image widgets, this could also become an option: in contexts, -when image data is retrieved in a very fast way.) - -*/ |